Question

In comparison to Mn\(^ {3+}\) ions Mn\(^ {2+}\) ions are more stable. Why?

Hint:

Half-filled and fully filled electronic configurations provide extra stability to ions due to exchange energy and symmetrical distribution.

Answer 1

Step 1: Consider electronic configurations.
- Mn (Z = 25): [Ar] 3d\(^5\) 4s\(^2\)
- Mn\(^{2+}\): [Ar] 3d\(^5\) (stable half-filled configuration)
- Mn\(^{3+}\): [Ar] 3d\(^4\) (unstable, not half-filled)
Step 2: Stability explanation.
Mn\(^{2+}\) has exactly half-filled 3d orbitals (3d\(^5\)), which is particularly stable due to exchange energy and symmetrical distribution. On the other hand, Mn\(^{3+}\) with 3d\(^4\) lacks this extra stability. Final Answer: \[ \boxed{\text{Mn}^{2+} \text{ ions are more stable than Mn}^{3+} \text{ due to half-filled 3d orbitals.}} \]